Remark 1 Different from the prior works, in which only some of the system parameters such as the number of RISs are multiple, our proposed RIS-aided cell-free network is the first one to simultaneously consider multiple antennas, multiple bss, multiple users, multiple riss and multiple subcarriers. It indicates that most of the prior discussed scenarios [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, are our special cases. Moreover, by simply setting \(M\) , \(U\) , \(N\) , \(B\) , \(R\) , \(K\) , \(P\)  to the required values in these special cases, our proposed joint precoding framework can serve as a general solution to maximize the wsr in these special cases. For instance, by setting \(B=1\) , \(P=1\) , and \(R=1\) , the proposed framework can be used to solve the wsr maximization problem in a single-carrier scenario where one BS assisted by one RIS is deployed to serve multiple users as discussed in [3]}.

